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A health technician analyses blood samples for tuberculosis testing in a high-tech tuberculosis lab in Carabayllo in Lima, Peru.
Researchers in South Africa and Indonesia are to embark on a groundbreaking new international study to investigate whether people with tuberculosis (TB) who show no symptoms are unknowingly spreading the disease.
Researchers say the major study is likely to change the way the transmission of the disease is understood and how it’s addressed by health systems globally.
The R300 million study, which will run for three years, is jointly funded by charitable foundations, Wellcome and the Gates Foundation.
Asymptomatic TB
Studies have shown that just more than half of all people who have active TB are asymptomatic and unaware of their status because they show no symptoms.
When an individual is asymptomatic, it means that the bacteria that cause TB are present in the lungs or sputum, but there are no symptoms or signs of sickness, such as coughing, fever and appetite loss.
In October last year, the World Health Organisation officially defined asymptomatic TB to serve as a practical definition for TB programmes and research.
Researchers say it isn’t clearly understood how best to find people with asymptomatic TB and whether this group of people can spread it to others.
Director for Clinical Trials at the Africa Health Research Institute (AHRI), Dr Limakatso Lebina, explains, “TB is often thought of as a disease that makes people very sick, with symptoms such as persistent cough and weight loss, but we know about half of the people with TB don’t feel ill at all.”
The study – named the Asymptomatic TB Transmission in Indonesia and South Africa – seeks to address some of these questions.
Researchers from the Africa Health Research Institute at Somkhele in northern KwaZulu-Natal and Padjadjaren University in Indonesia are to recruit 90 000 participants from households with children for the study.
The volunteers will take part in community-based TB screening, including chest x-rays.
Researchers say if health systems continue to focus on only those with symptoms who present themselves at clinics or hospitals when they fall sick, they will miss many people who might have TB and transmit the disease to others.
AHRI Infectious Disease physician-scientist, Professor Emily Wong, who is the study’s co-leader, outlines what the study aims to achieve.
“The first and foremost goal of the study is to define how much transmission occurs from asymptomatic TB – to show how that contributes to the ongoing transmission. If asymptomatic TB is a major contributor to transmission, we have to flip that and find efficient and cost-effective ways to go into communities and screen people.”
Treatment adherence
While the studies can help improve the understanding and treatment of the complex but curable disease, adherence to treatment remains one of the challenges.
Community TB activist Xolani Mngomezulu from Kwamsane says she couldn’t work for almost two years when she was diagnosed with TB nine years ago.
She and her younger brother both had to be hospitalised.
“I tell the community that if you don’t take your medication as prescribed, you are increasing the risk of spreading the bacteria.”
The researchers also hope to develop new diagnostics, such as requiring participants to wear masks for a short period to test exhaled breath.
-Report by Reneé Heine
